I have some M&T joints that I've made with a couple of homemade jigs over
the last couple of days. I am wondering whether I need to tighten up my
tenoning jig based on the fit. At first, I had to really push hard with my
hands to get the tenon in all the way, to where it seemed like no glue at
all would fit... now its just a bit loose. I'm not sure whether -in
between- would be perfect because I haven't added any glue yet and I don't
know how much expansion there will be.
So I'm wondering if anyone can explain in text how a joint like this is
supposed to fit? Is there an online resource that gives a good verbal
representation of this kind of thing?
Thanks,
Mike
Mike W. wrote:
<snip>
> So I'm wondering if anyone can explain in text how a joint like this is
> supposed to fit?
Or as some old sage once remarked:
If you need a hammer/mallet, tis too tight.
If you can tap it together with your hat, tis too loose.
Hand fit, and tis just right.
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"Tight" means mating the surfaces with no gap, what does that have to do
with the diameter of the pegs or the thickness of the tenon? The pegged
mortise/tenon, so long as it does not rotate, won't wrack, and bears weight
downward without the pin.
"Andy Dingley" <[email protected]> wrote in message
news:[email protected]...
> On Tue, 13 Jan 2004 03:54:44 GMT, "Eric Lund"
> <[email protected]> wrote:
>
> >Which makes sense, since the purpose is the peg is to pull the shoulders
> >tight.
>
> That's another question ! Some of my pegs are 1/4" diameter oak or
> apple, going through a 1/2" tenon in a table stretcher. Others are 1"
> oak, through a 3" tenon in a timber-framed building. If I "pull the
> shoulders tight" equally in each case, I'll pull the tenons off the
> table.
>
> --
> Do whales have krillfiles ?
Yes, just that the draw is its own clamp.
"Andy Dingley" <[email protected]> wrote in message
news:[email protected]...
> On Tue, 13 Jan 2004 09:05:39 -0500, "George"
> <[email protected]> wrote:
>
> >"Tight" means mating the surfaces with no gap,
>
> Not for a drawbored peg in a tenon - they're bored "over-tight",
> especially in green wood. But knowing just how much "draw" to use
> isn't always easy.
>
> --
> Do whales have krillfiles ?
In the Rogowski book , complete Illustrated Guide to Joinery, he
describes it this way:
"The fit of a tenon...is more like the fit of a good shoe rather than
a sloppy sneaker or a too-tight cowboy boot. The joint slides
together with firm pressure and may require a hammer to tap it apart.
On Mon, 12 Jan 2004 02:53:24 GMT, "Mike W."
<[email protected]> wrote:
>I have some M&T joints that I've made with a couple of homemade jigs over
>the last couple of days. I am wondering whether I need to tighten up my
>tenoning jig based on the fit. At first, I had to really push hard with my
>hands to get the tenon in all the way, to where it seemed like no glue at
>all would fit... now its just a bit loose. I'm not sure whether -in
>between- would be perfect because I haven't added any glue yet and I don't
>know how much expansion there will be.
>
>So I'm wondering if anyone can explain in text how a joint like this is
>supposed to fit? Is there an online resource that gives a good verbal
>representation of this kind of thing?
>
>Thanks,
>Mike
>
Probobobaly krill filters instead.
Art
"Andy Dingley" <[email protected]> wrote in message
> --
> Do whales have krillfiles ?
>
> So work it out. If you're starting to care about the fit of a M&T
> joint, then it's time to get your head around timber movement and
> understand how to predict just how much it will move.
>
> Hoadley's "Understanding Wood"
> <http://www.amazon.com/exec/obidos/tg/detail/-/1561583588/codesmiths-20>
> is the classic book here, or the US gov wood products handbook (Lee
> Valley sell a paper copy, or it's downloadable)
>
> Then you'll need a few cheap $5 air hygrometers for your living space,
> workshop space and timber storage space. Maybe a pin meter too, but
> these are expensive and less useful than you might think.
I suspect that you can get most of the way there w/o and investment in
technology.
If you can acclimate your stock well, (a month indoors before a project),
you should be able to do this by looking at a calendar. Here in the
Northeast, indoor heating will reduce relative humidity. I can expect my
stock to expand from it's current state if I mill and assemble it today. If
August it particuclarly humid, I can expect it to go the other way.
-Steve
On Mon, 12 Jan 2004 02:53:24 GMT, "Mike W."
<[email protected]> wrote:
>I don't know how much expansion there will be.
So work it out. If you're starting to care about the fit of a M&T
joint, then it's time to get your head around timber movement and
understand how to predict just how much it will move.
Hoadley's "Understanding Wood"
<http://www.amazon.com/exec/obidos/tg/detail/-/1561583588/codesmiths-20>
is the classic book here, or the US gov wood products handbook (Lee
Valley sell a paper copy, or it's downloadable)
Then you'll need a few cheap $5 air hygrometers for your living space,
workshop space and timber storage space. Maybe a pin meter too, but
these are expensive and less useful than you might think.
Armed with the knowledge of timber movement, you can start telling
whether your joints will get tighter or looser in the future. It
doesn't really matter how they fit right now -- it's going to change
when they sit in the central-heated lounge instead of the workshop.
There are all sorts of theories about how tight a joint should be on
assembly, and whether you should be able to assemble them repeatedly
by hand, or if you need a one-off with a mallet. Personally I think
anything that I can pull apart by hand is OK. Pegged tenons though
should need a mallet to drive the pegs in.
--
Do whales have krillfiles ?
On Mon, 12 Jan 2004 08:25:02 -0500, "Stephen M"
<[email protected]> wrote:
>I suspect that you can get most of the way there w/o and investment in
>technology.
I half agree with this. IMHO, a cheap (literally $5) _air_ hygrometer
and waiting for equilibrium is as good as, if not better than, a pin
meter that just tells you one reading on one day.
But you need something, because you have to make comparisons between
the workshop space and the living space where the piece will finally
end up.
--
Smert' spamionam
On Tue, 13 Jan 2004 03:54:44 GMT, "Eric Lund"
<[email protected]> wrote:
>Which makes sense, since the purpose is the peg is to pull the shoulders
>tight.
That's another question ! Some of my pegs are 1/4" diameter oak or
apple, going through a 1/2" tenon in a table stretcher. Others are 1"
oak, through a 3" tenon in a timber-framed building. If I "pull the
shoulders tight" equally in each case, I'll pull the tenons off the
table.
--
Do whales have krillfiles ?
Andy Dingley notes:
>>Which makes sense, since the purpose is the peg is to pull the shoulders
>>tight.
>
>That's another question ! Some of my pegs are 1/4" diameter oak or
>apple, going through a 1/2" tenon in a table stretcher. Others are 1"
>oak, through a 3" tenon in a timber-framed building. If I "pull the
>shoulders tight" equally in each case, I'll pull the tenons off the
>table.
Of course. So don't. Reduce the pull on smaller pieces. Which I am sure you
know.
Charlie Self
If God had wanted me to touch my toes he would have put them higher on my body.
http://hometown.aol.com/charliediy/myhomepage/business.html
On Tue, 13 Jan 2004 09:05:39 -0500, "George"
<[email protected]> wrote:
>"Tight" means mating the surfaces with no gap,
Not for a drawbored peg in a tenon - they're bored "over-tight",
especially in green wood. But knowing just how much "draw" to use
isn't always easy.
--
Do whales have krillfiles ?
"Mike W." <[email protected]> wrote in message
news:[email protected]...
> I have some M&T joints that I've made with a couple of homemade jigs over
> the last couple of days. I am wondering whether I need to tighten up my
> tenoning jig based on the fit. At first, I had to really push hard with
my
> hands to get the tenon in all the way, to where it seemed like no glue at
> all would fit... now its just a bit loose. I'm not sure whether -in
> between- would be perfect because I haven't added any glue yet and I don't
> know how much expansion there will be.
>
> So I'm wondering if anyone can explain in text how a joint like this is
> supposed to fit? Is there an online resource that gives a good verbal
> representation of this kind of thing?
>
> Thanks,
> Mike
>
>
David Marks uses a slip fit on his show, so he can slide the tenon in and
out of the mortice by hand. Works for him.
Cheers,
Eric
From what I've heard, the rule is this: You should need to tap it in
with your shop mallet, but you should only need light taps. However,
I like to be able to put it together without the mallet, but still
snug enough to stay put when I let go.
But anyway... if the joint can't hold its own against gravity, it's
too loose. If you can't get it apart to put the glue in after test
fitting, it's too tight.
DJ Delorie responds:
>From what I've heard, the rule is this: You should need to tap it in
>with your shop mallet, but you should only need light taps. However,
>I like to be able to put it together without the mallet, but still
>snug enough to stay put when I let go.
I do NOT like having to use a mallet to tap fit a joint for a test. A tight
push fit with hand pressure, albeit a lot of it, is more sensible to me.
>But anyway... if the joint can't hold its own against gravity, it's
>too loose. If you can't get it apart to put the glue in after test
>fitting, it's too tight.
Makes sense.And a tight push fit will hold against gravity unless the piece
being held is huge.
Charlie Self
If God had wanted me to touch my toes he would have put them higher on my body.
http://hometown.aol.com/charliediy/myhomepage/business.html
I agree wholeheartedly ... especially the part where it "may require a
hammer to tap it apart". Most of my M & T joints will go together with firm
hand pressure when dry fitting, however, even those on the loose side may
require a tap or two with the deadblow to pull apart ... when that happens,
you know you've got a good fitting joint.
--
www.e-woodshop.net
Last update: 1/02/04
"jev" wrote in message
> In the Rogowski book , complete Illustrated Guide to Joinery, he
> describes it this way:
>
> "The fit of a tenon...is more like the fit of a good shoe rather than
> a sloppy sneaker or a too-tight cowboy boot. The joint slides
> together with firm pressure and may require a hammer to tap it apart.